Commit 3595599f authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by Jakub Kicinski
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net: xdp: Disallow attaching device-bound programs in generic mode 



Device-bound programs are used to support RX metadata kfuncs. These
kfuncs are driver-specific and rely on the driver context to read the
metadata. This means they can't work in generic XDP mode. However, there
is no check to disallow such programs from being attached in generic
mode, in which case the metadata kfuncs will be called in an invalid
context, leading to crashes.

Fix this by adding a check to disallow attaching device-bound programs
in generic mode.

Fixes: 2b3486bc ("bpf: Introduce device-bound XDP programs")
Reported-by: default avatarMarcus Wichelmann <marcus.wichelmann@hetzner-cloud.de>
Closes: https://lore.kernel.org/r/dae862ec-43b5-41a0-8edf-46c59071cdda@hetzner-cloud.de


Tested-by: default avatarMarcus Wichelmann <marcus.wichelmann@hetzner-cloud.de>
Acked-by: default avatarStanislav Fomichev <sdf@fomichev.me>
Signed-off-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20250127131344.238147-1-toke@redhat.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 8c670bdf

net/core/dev.c

+4 −0
Original line number Diff line number Diff line
@@ -9924,6 +9924,10 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack 
			NL_SET_ERR_MSG(extack, "Program bound to different device");

			return -EINVAL;

		}

		if (bpf_prog_is_dev_bound(new_prog->aux) && mode == XDP_MODE_SKB) {

			NL_SET_ERR_MSG(extack, "Can't attach device-bound programs in generic mode");

			return -EINVAL;

		}

		if (new_prog->expected_attach_type == BPF_XDP_DEVMAP) {

			NL_SET_ERR_MSG(extack, "BPF_XDP_DEVMAP programs can not be attached to a device");

			return -EINVAL;